I am vile. This is true wisdom. This is "the end of the Lord" (James 5:11), and the "end" of this whole book.
what... ? Figure of speech Erotesis. App-6.
lay mine hand, &c. Symbolic of silence and submission.
Related Commentaries of Job 40:4
Job 40:4
4 Behold, I am vile; what shall I answer thee? I will lay mine hand upon my mouth.